Mold base



Nov. 2s, 195o G. H. Brick ET AL 2,531,965

MOLD BASES Filed March 4, 1949 3 sheets-sheet 1 fi 1 H I :1 /0 I l' T?mr I l I l/ "l IIN", I III V Il; Il I i y I I A Y l a 9 rh IN1 I Il" l,3 5Z^- 4 l,

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ATTO R N EY Nov., 28, 1950 G. H. BECK r-:T AL 2,531,965

MOLD BASES Filed March 4, 1949 5 Sheets-Sheet 2 INVE TORS ATTCRN EY Nov.28, 1950 G. H. BECK ET AL MOLD BASES 3 Sheets-Sheet 5 Quell@ Quinn@Filed March 4, 1949 ATTORNEY Patented Nov. 28, 1950 UNITED STATES PATENTG'FFICE 2,531,965 MOLD BASE George H. Beck, Maplewood, and Julius Z.Foris, Union, N. J.

Applicationv March 4, 1949, Serial No. 79,537

6 Claims.

' This invention relates to standard mold bases for plastic molds or fordie casting dies.

The movable or ejector portion of a standard mold base conventionallycomprises a plurality of plates which are intersecured to form suchmovable portion. An ejector plate including ejector pins is arranged forsliding movement within and in respect to the mold base. The immovableor front portion of the mold base generally has leader pins disposedtherethrough and which further extend throughout the plates of the rearportion.

The connection of a standard mold base to a molding machine involvesprecision operations in that the separate plates require considerablesurface machining in order that they all meet accurately. Precision ofalignment of such plates is of extreme importance because the leaderpins, ejector pins and other elongated elements reciprocate throughaligned openings in these plates. The assembly of these parts is anoperation requiring considerable time and careful attention.

According to the present invention, a simplified standard mold base isprovided which eliminates a large part of the machining heretoforerequired in producing the mold base of separate plates. The assembly andmaintenance of the mold base are further reduced to a minimum. This isaccomplished by a special arrangement wherein a unitary structuresupplants at least three separate components plus screws and dowels ofthe conventional mold base. Such unitary structure is so formed as toeliminate the conventional 4separate anchor plate, parallels or spacers,back-up plate, and rear cavity plate. These find their counterparts in aunitary structure which is further formed with clamping recessesheretofore provided by overhang of the anchor or clamping plate orslotting of the parallels. In order to render such a unitary structurepossible, the instant mold base dispenses with a back stop for limitingrearward movement of the injector plate. If a conventional back stopwere employed, the assembly of the injector components into the m-oldbase would be rendered quite difcult because such ejector componentsusually operate between the rear anchor plate and the back-up plate. Theinstant invention eliminates such a rear anchor plate or any other typeof rear stop. Rearward movement of the ejector plate is limited by theparticular formation of the push-back pins which are connected to theejector plate. Such ejector pins are further made variable in effectivelength so as to accommodate various thicknesses in the articles to bemolded.

The invention will be further understood from the following descriptionand drawings in which:

Fig. l is a front View in elevation, partly broken away, of a mold basemade according to the instant invention.

Fig. 2 is a cross-sectional view taken along the lines 2 2 of Fig. 1.

Fig. 3 is a cross-sectional view showing the ejector plate and push-backpin assembly as 'seen along the lines 3 3 of Fig. 5.

Fig. 4 is a cross-sectional view taken along the lines 4 4 of Fig. 2.

Fig. 5 is a top plan view of the rear cavity or retainer plate asconnected to the remainder of the base.

Fig. 6 is a top plan view of the front cavity or retainer plate.

The immovable portion of the molding base comprises the usual locator,nozzle and sprue bushing or transfer pot as shown at I, the anchor plateII, the pressure pads 9, and the front cavity retainer plate I2. Theseare suitably connected in any conventional manner. Leader pins I3 areconnected to anchor plate II and extend outwardly for their aligningfunction.

The movable or ejector portion of the mold base comprises a unitarystructure I4 which eX- tends throughout the length of such portion.Accordingly, the mold base does not employ those plates hereinabovedescribed.` Structure I4 incorporates the function of the rear cavityplate, the back-up plate, and the parallels or spacers as well as addingadditional functions as will hereinafter appear. Thus, the sides or armsI5 and I6 are formed with one or more recesses, such as Il. Suchrecesses permit clamping of the mold base to a conventional or diecasting molding machine and thereby eliminate the requirement for theoverhang of the anchor or clamping plate or slotting of the parallels.Structure I4 may be shaped like an inverted U so that the arms YI5 andI6 appear as platforms supporting the transverse structure which carriesthe molds as in nest I8 which may be rough cast to suitable shape andsize. A mold cavity I9 is also illustrated. Ejector plate 25 is disposedwithin the opening of structure I4 so as to slide therein between thearms I5 and I6. It is provided with a stop bar 26 and a pin plate 2l,the function of which is to support the push-back pins 28, 29, 35 and 36as well as the knock-out pins 30, a plurality of which are provided toeject the plastic or metal molding as is conventional. The shafts 3|,

32 and 33 are cnnected to the transverse portion of structure I4 as bybolts 34. It will be understood that the ejector mechanism slides onsuch shafts by having openings therethough for this purpose. Thepush-back pins serve their usual purpose of causing aligned retractionof the ejector plate when the mold is brought together for ejection orcompression.

In Figi 73 is illustrated the connection ofthe push-back pins andknock-out pins to the ejector plate 25. The knock-out pins operatethrough suitable openings in the transverse portion of structure I4 soas to enter the molds such as mold I9 for the usual purpose ofvdislodgingthe formed article. Push back pins such as l35 may 'v be astandard stripper bolt. All of the push-back pins are renderedadjustable as to length by being received in threaded openings All ofejector plate 25 and by being provided with nuts el by which thelengthof the push-back pins vmay be adjusted. Subsequent adjustments maybeymade changing the lthickness. of stop-bar 26- and turning of bolts 35.This is an important feature in determining the extent of retractabilityof the ejector plate or the degree of'rprotrusion of thepush-back-pin inrespect to the rear cavity retainer portion.

l The .provision of the large heads.ofthepush back pin maintains theassembly-of vkthe mold base notwithstanding the `fact. that no. clampingor anchor plate is provided in themovable portion of the mold base.-Assembly of themold base is thus facilitated because the ejector plateneed merely be inserted inplace as Vvvill-be vevident from Fig. l andthe push-back pins may-be inserted `through the rea-rI cavitymolding-surface and threaded into the openings 113 so as-to maintain theassembly of the moldbase.

In Fig. 5 is illustrated a top plan view ofthe rear `cavity moldingsurface. The injected substance lows through thegates 513 `as willunderstood by those skilled in the art and such substance is directedinto molds l5 in the rear cavity retainer surfaceinthe conventionalmanner.

Unitary structure le may be formedof semisteel, steel or other metals asby a casting` process and thereafter machined-so that itis of aprecisionsuitable for its purpose. Accordingly, pads are formed integral withstructure i4 at strategic places whereby the structuremay bebrought tothe requireddimensionaand at required angular relationship with eachother and the rearcavity molding surface. Thus, pads 5l, 52,133 and '54(Fig. l) are formed on all four. sides of the upper portion ofstructure' M. The lower surface of the transverse structure -is alsoprovided with a pad- 55 because this surface meets the secondaryejectorl plate 21 when the lejector plate is inwardly operated. Theprovision of such .pads at the places indicated insures that the unitarystructure, which may be more or less roughly cast, is4

rendered suitable for precision operations by a minimum of machining.

InlFig. 6 issho'vv'n the front cavity'retainerplate l2,` pressure pads3, "recesses-56, and' leader pins I3. V"li'hese elemtns areconventional.

1A 'mold basesuch ias disclosed "above has Vbeen foundtobe effective forinjection,`compression, transfer, plunger, plastic molds "andpractically all types and conditions ofplasticsmolding'and die castingsalthough it is in large part 'pre-- formed Aas, by a casting process'insuch a way that a' 'great deal of high skilled operations are avoided.Furthermore, .a superior mold'is .provided. "Many changes'loromissionsmay readily suggestfithemselves andit' is' therefore 'desiredto heads formed on the free ends of said push-back pins, said push-backpins being slidable in elon- Agated openings formed in the transverseportion. lorfsaid'unitary structure, and shoulders formed :.in'saidelongated openings for engaging said enlarged` heads so as to contactand predetermine `rearwardV movement of said ejector plate, saidpush-back pins having their connected ends threadedly engaged withcomplementary openings in saidf ejector plate, such connection. servingfto regulate -the effective length 4of said push-back.

pins.

2. A mold base -accordingto claim l and Wherein the limit ofrearwardmovement of said-ejector,

plate is :at substantially the Same lineas the free'endsof the armsofi-said inverted U-shaped unitary structure, -said arms .being formedwith depressions ltherein to ypermit clamping -of the unitary structureand ejector plate to a molding machine.

3. A mold base according to claim 2 and including a'front anchorsplateand a frontcavity retainer-*plate secured thereto, and leader pinsimmovably connected through said anchor plate and extending therefrom soas to enter yinto complementary openings in the arms of said unitarystructure approximately one-third the length of saidarms.

4. A .mold base comprising an inverted 'U- shaped unitary structurehaving vintegralv'supportingsarmsiand a transverse portion, van ejectorplate mounted for reciprocating movement within the inverted U-shapedopening of the structurebetween Aand parallel to said-"arms, push-backpins :connected to said ejector plate, enlarged heads formed on the freeends of :said push-backzpins, -said push-'back pins being slidable inelongated openingsiormed in the trans-4 verse :portion of v.said unitarystructure', shoulders formed'in said elongated openings for engagingsaid enlarged heads soas to limit rearward'moveme'nt-of said ejectorplatasaid pushbackA pins having their connected-ends threadedly engagedwith complementary 'openingsffinsaid ejector plate, such connectionserving-to regulate 'the'eiective' 'length of said push-back pins,aniopposing moldibaseportion for immovable conn'ectionto a moldingmachine, ysaid opposing portioninoluding a front anchor platetransverseportion rso asV to permit machining thereof until the Vmold base reachesltheproper dimensions.

5. A mold-base according to claim 4 andincludinga pair of concavedepressionsformedfon the outer portionsof each arm below the padsthereof, said. depressions serving as clamping, means forconnectingthe-mold base-to a-mo1d g 1'5' ing machine.

6. A mold base comprising an inverted U- shaped structure havingsupporting arms and a transverse portion, an ejector plate mounted forreciprocating movement within the inverted U-shaped opening of thestructure between and parallel to said arms, push-back pins connected tosaid ejector plate, enlarged heads formed on the free ends of saidpush-back pins, said push-back pins fbeing slidable in elongatedopenings formed in the transverse portion of said structure, andshoulders formed in said elongated openings for engaging said enlargedheads so as to contact and predetermine rearward movement of saidejector plate, said pushback pins having their connected ends threadedlyengaged with complementary openings in 6 said ejector plate, suchconnection lserving to regulate the effective length of said push-backpins.

GEORGE H. BECK.- JULIUS Z. FORIS.`

REFERENCES CITED The following references are of record in the file ofthis patenti UNITED STATES PATENTS Number Name Date 1,584,171 Herrick-11 May' 1i, 1926 1,916,692 -Scribner' a- 1;.7-- Julyv 4, 1933 2,377,128Burgess May 2 9, 1945 2,419,089 Quarnstrom Apr.- 15, 194'?

